The field of horseshoeing generally is considered an art or a skill, rather than a science, since traditionally all of the steps inherent in the process of applying a set of horseshoes to the feet of the horse is based upon a visual examination by the farrier. For example, the farrier looks at the bottom of the foot in order to determine its flatness and the plane of the bottom of the foot relative to the leg of the horse. After this observation is made, the farrier makes any necessary corrections by peeling, cutting, filing or otherwise removing part of the bottom of the hoof. The horseshoe then is nailed in place to the corrected bottom of the hoof. Because of the nature of this process, however, errors are frequent; and such errors can lead to improper wear of the horseshoe, and, more seriously, may lead to actual damage of the leg and foot of the horse.
To avoid such errors, it is particularly important for the farrier to measure the extent of side-to-side balance of the foot. A balanced foot assures that the foot strikes the ground flat and evenly. This assures that there will be optimum support from the foot, up through the rest of the bony column of the leg. A foot that is in proper medial/lateral balance will help maintain proper alignment of the leg joints, thereby exposing them to less stress rotation and deviation. This also will provide these joints with optimum flexion. Improper medial/lateral balance causes the foot to strike the ground unevenly, and induces undesired stress, rotation and deviation in the joint of the leg of the horse.
Precise medial/lateral balance is very difficult to determine by the naked eye. Thus, a great deal of skill is required on the part of the farrier to visually obtain the desired results. Without such skill, disastrous results sometimes occur.
The United States patents to Finnegan U.S. Pat. Nos. 4,813,148 and 5,027,520 are directed to devices to help in determining the flatness of the foot of a horse in assisting the farrier in making necessary corrections. These devices are cumbersome and involve multiple parts, which must be adjusted while the device is attached to or placed on the foot of the horse. Because of the somewhat complex nature of these devices, they are not readily carried on the person of the farrier; and because of the multiple adjustments which must be made, they are difficult to use. Some horses will not remain quiet long enough to permit a farrier to make the necessary adjustments using tools of the types disclosed in these patents.
The United States patent to Beaston U.S. Pat. No. 4,214,370 is directed to a hoof alignment tool for measuring the size and determining the shape of a horse""s hoof. This tool includes a pair of pivotal arms and a straight edge member to permit the tool to be closed around the outer hoof wall to measure both the hoof length and the angle of the wall with respect to the base of the hoof. The device of this patent, however, requires it to be manipulated and clamped onto the foot of the horse in order to effect the necessary measurements. Because of the adjustments which must be made in using this tool, it again is cumbersome and difficult to use. As with the tools of the Finnegan patents mentioned above, it also is sufficiently bulky that it is not readily carried on the person of the farrier for convenient use and application.
Four other United States patents are directed to various devices for measuring and leveling horses"" feet, or for altering the leg conformation by changing the angle on the bottom of the foot. These patents are: Kearns U.S. Pat. No. 583,706; Millett U.S. Pat. No. 602,952; Holmquist U.S. Pat. No. 832,060 and Behney U.S. Pat. No. 4,227,311. All of the devices disclosed in these patents comprise multiple parts which require set screw or other types of adjustments by the farrier. They clamp onto the horse""s foot, which presents a safety problem in the event that the horse should suddenly kick or move its foot while the device is either being applied to or removed from the foot of the horse. In addition, all of them are relatively cumbersome and bulky; so that they are not readily carried on the person of the farrier for quick and simple application.
It is desirable to provide an instrument for assisting a farrier in determining medial/lateral balance, symmetry or asymmetry, and to enable the farrier to precisely correct imbalance or other flaws with an instrument which is simple, accurate and easy to manufacture and use, as well as being durable and inexpensive.
It is an object of this invention to provide an improved farrier""s instrument.
It is another object of this invention to provide an improved farrier""s sighting instrument for simply and quickly measuring the medial/lateral symmetry or asymmetry of the foot of a horse.
It is still another object of the invention to provide an improved farrier""s instrument for enabling a farrier to quickly determine that a horseshoe is correctly attached to the hoof of a horse.
It is a further object of this invention to provide an improved lightweight, portable farrier""s sighting instrument which assists a farrier in measuring, trimming, filing and clipping the hoof of a horse in a correct manner, which additionally allows the farrier to measure the shoe for balance, length, flatness and symmetry/asymmetry prior to attaching the shoe to the hoof of the horse, and finally, to assist the farrier in attaching the shoe to the hoof.
In accordance with a preferred embodiment of the invention, a farrier""s sighting instrument is comprised of a flat, transparent plate which has at least one straight edge, and which is dimensioned to overlie the foot of a horse. The flat, transparent plate has a plurality of parallel indicia lines in the plate; and these lines are perpendicular to the one straight edge. The lines also are spaced from one another by a uniform distance. A stop plate is attached to the one straight edge and extends above the surface of the flat, transparent plate in a plane which is perpendicular to the plane in which the parallel indicia lines are located. These simple elements of the tool permit a farrier to rapidly determine the symmetry/asymmetry of a horse""s foot, and to measure the shape of a horseshoe prior to applying it to the foot, as well as assisting in proper attachment of the horseshoe to the foot of the horse.